US2943293A - Electrical connector - Google Patents

Description

C. H. BUCHER ETAL ELECTRICAL CONNECTOR June 28, 1960 3 Sheets-Sheet 1 Filed June 20, 1957 INVENTORS (31ml H. liucnlln; GEQRGE J. HANDEI.,JR.

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FIG.8

June 28, 1960 .B CHER T June 28, 1960 FIG.I3

CARI. ll. Bucrmm GEORGE J. HANDEL, JR.

n ed Stat a n ELECTRICAL CONNECTOR Carl H. Bucher, Harrisburg, and George J. Handel, Jr.,

Camp Hill, Pa., assignors to AMP Incorporated, Harrisburg, Pa.

Filed June 20, 1957, Ser. No. 666,920

Claims (Cl. 339-223) This invention relates to electrical connectors and terminals, to crimped electrical connections, and to methods of making crimped electrical connections.

It is an object of the invention to provide an improved crimped connection between the conducting core of a wire and a connector or terminal. A further object is to form an improved connection incorporating both an insulation supporting ferrule for a wire and a crimped connection between the conducting strands and the connector. A further object is to form a crimped connectlon in which the axis of the wire is in substantial alignment with the axis of the crimped connection which connects the conducting core or strands of the wire and the connector axis. A further object is to provide a connector which can be crimped onto wires of varying sizes. A further object is to provide a crimped connection by means of which a relatively large cylindrical terminal can be crimpedonto a relatively small diameter wire without the need of intermediate adapters. A still further object is to provide a connector having a substantially uniform cross section in its crimping zone which uniform cross section upon crimping forms both an insulation supporting ferrule for the wire insulation and a mechanically strong, electrically conductive connection between the strands of the wire and the connector.

These and other objects of the invention will be apparent from the vfollowing detailed description of the invention and from the annexed drawings in which:

Figure -l is a plan view of a flat blank formed from sheet metal and from which connectors in accordance with the invention are produced;

Figures 2, 3 and 4 show a plan view, a side view, and a perspective view respectively of a connector terminal formed from the blank of Figure 1;

Figures 5 and 6 show a side view and a perspective view respectively of the connector of Figure 2 as crimped onto the end of a wire;

Figure 7 is a view taken along the lines VI1 -VII of Figure 5;

Figures 8 and 9 are views taken along the lines VIII- VIII and IXIX of Figure 2;

Figure ,10 is a fragmentary sectional view taken through a die assembly for crimping the connector embodiment shown in Figure 2 and showing such a connector positioned Within the dies for crimping, this view showing the dies in their open position before crimping; a t Figure 11 is a view similar'to Figure 10 showing th diesin the closed position with a crimped connector positioned between the several cn'mpingdies;

Figure 12 is a view taken along the lines XII-X11 of Figure 10;

Figure 13 is a view similar'to Figure 12 but showing v the dies in the partially closed position;

Figure 14 is a view taken along the lines XIVXIV of- Figure 11; e

Figure 15. is a view taken alongthe lines XV-XV of Figure 10;

2,943,293 Patented June 2 8, 1960 P we Figure 16 is a view similar to Figure 15 but showing the dies in the partially closed position;

Figure 17 is a view taken along the lines XVII-XVII of Figure 11;

Figure 18 is a sectional view through a plug board and showing the crimped connector of Figure 6 positioned within the board; and

Figures 19, 20, and 21 are views taken along the lines XIX'--XIX, XX-XX, and XXI--XXI of Figure 18.

. The blank from which the illustrative embodiment of the terminal is produced comprises a leading end 2 which is subsequently formed into a projectile-like terminal contact portion and a trailing section 4 which is subsequently formed into a trough-like section adapted for crimping onto a wire. This blank is advantageously formed from sheet metal such as brass or copper by progressive die forming operations and provides parallel edges 6 having semi-circular cut-outs 8 and tapering frontal portions which define a pair of noses 10 on each side of the axis. A central nose 12 projects forwardly from between the noses 10 and is connected by means of a slug or thin strip 14 with the trailing end of the next adjacent blank. On each side of the axis of the blank converging slots 16 are provided and a O-shaped slot 18 is punched out near the end of the forward portion, the ends of this C-shaped slot being in alignment with the axes of the converging slots 16 as shown.

.Notches 19 are provided on the edges of the blank between the leading end and the trailing end and these notches merge with. the parallel edges 20fof the trailing end. Parallel slots 22a, 22b extend transversely in the trailing endand between these slots are provided aplurality of depressions 23 which assist in retaining the wire within the crimped connection as explained in detail in the copending application of Kemper M. Hammell, Serial No. 604,544, filed August 16, 1956. Between the rearward slot 221) and the rear edge .26of the blank are provided a plurality of protrusions 24 in the form of dimples, three such dimples being provided in the disclosed embodiment, one being positioned on the axisof the blank and one being positioned on each side thereof. The trailing end or edge 26 of the blank is notched as shown at 28 and the previously mentioned connecting slug 14 enters this edge between these notches. A pair of relatively narrow notches 25 extend inwardly from edges 20 portion 30.and a trough-like'trailing portion 33. Nose 30provides an outwardly slanted tab 32, which is formed by severing along a line connecting these slots 16 with the slot 18 and bending the thus severed section of metal outwardly, and also provides a circular opening 31 along its top seam as viewed in Figure 2, formed by the cut-out sections 8 in the blank. It should be mentioned at this point that while the invention is particularly disclosed with reference to a connector having the projectile-like terminal portion on its end, the invention itself is applicable to alternative types of terminals or connectors, e.g,,. terminals providing ring-tongue or space ends adapted to be secured to a stud or the like and to terminals having specializedcnd portions of any of the wide variety of available forms.

The trough-like ferrule-forming or crimp-forming portion 33 of the connector provides sidewalls 34 connected by a base which is identified in its rearward portion by 36b and in its section between slots 22a, 22b by 36a.

amazes the rearmost slot 22b. Obliquely directed flanges are formed as shown at 38 extending from the trailing edge of the terminal which flanges function as stops to prevent insertion of the terminal into a plug board beyond the desired point. These flanges can of course be dispensed where the invention is incorporated into alternative types of terminals and where the terminal is not adapted to be inserted into a plugboard.

in affixing the uncrimped connection onto a conductor having a stripped end, the conductor is positioned between sidewalls 34 with stripped portions extending between slots 22a, 22b and with unstripped portions or insulated portions extending rearwardly beyond the rearmost slot 22b. The electrical crimped connection between the connector and the stripped end of the wire is formed by indenting the base portion 36a inwardly upon itself to form a substantially flat longitudinally extending web 42 (Figure 7). This web is indented in most instances to a depth suflicient to provide depending flanges 44 which are bent downwardly as shown at 43 from the web, the flanges in turn being reversely bent at 46 to merge with the sides of the crimp as shown at 17. The marginal edge portions of the sidewalls are curled towards each other as shown at 48 and reversely curled downwardly towards the floor of the web as Shown at 50. The conducting strands 52 are thus securely locked between the web and the curled sidewalls of the crimped connection.

The portion of the trough-like part of the connector which lies rearwardly of the rearmost slot 22b is deformed in a somewhat different manner than the zone between the slots 22a, 22b, to form an insulation supporting ferrule for insulated parts of the conductor indicated by C. In the finished connection as shown in Figure 6, the base 36b of the original uncrimped connector may be substantially unchanged from its original curved shape, but the sidewalls are bent inwardly towards each other asshown at 54 until their edges are brought into abutting relationship. This reformation of this rearward section of the trough-like cross section reduces its cross sectional area and brings the interior surface of this rearward portion into surrounding and confining relationship with the insulation on the Wire. The protrusions or dimples 24 assist in confining the insulation as shown in Figure 21 in that they are pressed against the surface of the insulation and tend to compress it to hold the wire and take up the tensile stresses which might be applied thereto and transmit these stresses directly from the insulation to the connector rather than from the wire through the electrical crimp between slots 22a, 22b to the connector. It is of course, advantageous to transmit tensile stresses from a wire through the insulation to the connector rather than through the conducting strands to the connector in order to avoid damage to the electrical crimp. An additional function of these dimples is to prevent bending of the strands on an extremely short radius when the wire is bent at its point of entry into the connector. These dimples also prevent severe twisting of the wire strands such as might cause them to work harden and fracture.

it will be apparent that the crimped connection of Fi ure 6 might be formed by a variety of methods and tools however in manufacturing leads having terminals on one or both ends it is desirable to perform the operations in an automatic or a semi-automatic machine providing a single die set by means of which all of the crimping operations can be carried out upon a single closure of the dies. In Figures 17 there is shown in detail such a die set and the manner in which the terminal is crimped to produce the completed connection of Figure 6. The dies in these views are shown fragmentarily and it is understood that the arrangement taught by these views might be used on a simple hand operated press, a semi-automatic press, or a fully automatic press and feeding means for manufacturing electrical leads as taught for example in the copending application of Harold A. Kerstetter et al., Serial Number 562,198, filed January 30, 1956.

In the disclosed tooling for crimping the connector, there is provided an upper die set relatively movable towards a lower die set, and means for feeding a terminal between the dies when they are open, so that a wire end can be positioned, either manually or automatically, within the terminal and the dies closed to form the completed termination. The upper die set, as shown in Figure 10, provides an upper crimping die 56 for the insulation supporting portion of the connection, an upper crimping die 58 for the electrical connection between the conductor and the connector, a hold down 62 for retaining the forward end of the connector during crimping, a slugout blade 66 for severing the connecting slugs as the dies are lowered, and suitable spacers 60, 64, for achieving the proper spacing of the dies. The lower die set comprises an anvil 68 adapted for cooperation with ferrule forming crimper 56, anvils 70, 72 adapted for cooperation with crimping die 58, a resiliently mounted support 73, and a shearing blade '74 for cooperation with upper shearing blade 66. Anvils 68, 70 and 72 and shearing blade 74 are fixedly mounted in the disclosed embodiment while support 73 is spring biased to the position of Figure 10 but can be depressed to the position of Figure 11 as explained below. This support 73 provides a bearing surface at 75 and a supporting edge at 77 for supporting the nose portion of the terminal during crimping. A suitable support 76 provides a feed track for a succession of terminals, the next adjacent one of the terminals from one in the die set being shown in Figure 10. 'It is understood that the lower die set and support 76 will ordinarily be secured onto the bed or platen of a suitable press and the upper dies will be carried by a tool holder which in turn will be carried by the ram of. the press. The feeding means for feeding the terminals will in many circumstances be coordinated for movement with the descent of the ram so that an uncrimped terminal is fed between the dies as the ram travels through its cycle, as taught in the aforementioned Kerstetter et al. application.

At the beginning of the crimping cycle, the parts will be shown in Figure 10 with an uncrimped terminal positioned between the open dies. Supporting anvil 70, as shown best in Figure 12, has an upper supporting surface which provides a ridge 78 bordered on each side by edge portions 79 which support the base of the terminal between slots 22a, 22b, while the projectile-like frontal portion of the terminal 30 is supported at 75 and 77 on resiliently mounted support 73. The dies 68, 72 are somewhat lower than the die 70 so that the rearward portion of the terminal is supported only in the zone between the slots.

Crimping die 58 which forms the electrical connection between the wire strands and the connector has inwardly converging sidewalls 80 which merge with slightly tapered sidewalls 82. Tapering sidewalls 82, in turn, merge with arcuate surfaces 84 at the top of the die cavity and these arcuate surfaces curve towards each other to form a central cusp 86. As the ram and the die 58 descend, as shown by Figures 12 and 13, the sidewalls 34 of the terminal between notches 19 and 25 are gathered and flexed towards each other by the side 82 of the die until the edges of the sidewalls contact arcuate surfaces 84 at the roof of the die cavity. At that point the downward components of the forces acting on the terminal becomes sufficient to deform the base portion 36a over central ridge 78 of die 70 thus forming web 42 and its depending flanges 44. As this web is formed, the entire terminal moves downwardly from the position of Figure 10 to the position of Figure 11 and upon further descent of the ram, upstanding sidewalls 34 between notches 19 and 25 are curled by die 58 inwardly towards each other and finally downwardly towards the internal surface of web 42 to grip tightly the wire strands and form the electrical connection between the connector and the conductor. It

will be noted that as the terminal moves downwardly from the position of Figure to the position of Figure 11 as a result of the formation of the web on its bottom, the portion of the base of the trough-like section is in front of the foremost one of the slots 22a and is lowered onto the upper surface of anvil 72 and resiliently-mounted support 73 moves downwardly during this interval with the terminal.

During the latter stages of the descent of the ram the insulation supporting ferrule on the end of the connector is formed by die 56 as shown in Figures 15-17. This die provides gathering portions 90 similar to gathering portions 86 of die 58 and sloping sidewalls 92 which merge into a roof section 94 of substantially semi-circular cross section. The cooperating lower anvil 68 provides a simple arcuate upper surface 88 dimensioned to conform to the base of the connector and support it during the crimping operation. Initially as shown in Figure 10 this rearmost portion of the connector beyond the rearrnost one of the slots 22 is positioned above the surface 88 of die 63. As the connector is indented onits base between slots 22 and as it is lowered relative to the lower die set, the base at the rear of the connector is brought down onto surface 88 as shown in Figure 16. Thereafter the sidewalls are bent toward each other as they are forced inwardly by tapering sidewalls 92 and finally by the semi-circular surface 94 of the die. The strengthening or stiffening effect of dimples 24 aids in causing this portion of the ferrule to assume a segmental cross section, as shown in Figure 17, in the embodiment shown. It is within the purview of the invention, however, to form an insulation support of circular cross section if desired. I

Anvil 72 is of substantially the same shape in cross section as anvil 68 and supports the frontal portion of the trough-like section of the connector during the final crimping. During this final crimping it is also desirable to apply a downward force onthe end of the connector in order to prevent its being bent in the zone between the crimped section and end of the nose. To this end the hold down-device 62 contacts the frontal portion of the connector as shown in Figure 11 and prevents any substantial flexure or permanent bending as a result of reaction to the crimping forces applied by crimpers 56, 58 Hold down device 62 is of substantially the same shape as crimping die 56 and is not shown specifically in section. Shearing blade 66 during the initial portion of the descent shears slug 14 at the plane between the face of this blade and block 76. The entire connector then moves downwardly with the slug 14 afiixed to its front and this slug is subsequently sheared as shown at Figure 11 as it is forced against the shearing edge of blade 74.

It will be noted that in accordance with the foregoing description, the crimped connection of the invention is formed by first indenting the base of the ferrule between slots 22a, 22b, and subsequently curling the sidewalls between the slots to form the electrical connection and bending the sidewalls near the end of the ferrule-forming portion to form the insulation support. It should be understood that this sequence of the steps is not critical and that the invention can be practiced by first curling the sidewalls and then indenting the base. Where the invention is practiced by the use of a relatively high speed press, the indenting and curling operations will take place within a small fraction of a second and the operation will take place substantially simultaneously.

The completed connector of the type shown in the illustrative embodiment is adapted for use in a panel 96 providing a circular opening 98 dimensioned to receive the plug which is inserted through the opening until tab 32 springs outwardly against the back side of the board to lock the connector into place, the wings or flanges 38 functioning as a stop in this connection to prevent insertion of the connector beyond the desired point. As

shown by the'sectional views 'of Figures 19-21, the cirso that in this area the connector does not contact the sidewalls of the opening. This arrangement is desirable for the reason that sidewalls of this crimped area do not have the same curvature as the walls of opening 98 so that if the maximum dimension of the crimp itself'were the same as the diameter of the opening it would be difficult to withdraw the plug or possibly to insert it. The insulation supporting ferrule as shown in Figure 1, however, provides an arcuate base having substantially the same radius as the radius of opening 98 so that it bears against the surface of this opening over a substantial area; In addition, the'sidewa'lls, particularly at the apex of their meeting edges, will also bear against the F opening surface and substantially preclude wobbling or movement of the plug within the opening as if this rear portion or insulation supporting ferrule were of circular cross section.

The invention is particularly useful and provides marked advantages when incorporated into plug-type terminals of the type shown in the drawing. Plugs of this type generally are ofia relatively large diameter relative tothe diameter of the wires withwhich they are used and are advantageously formed from strip material by progressive die forming operations. Where the plugs are formed in this manner, the portion of the plug which is crimped onto the wire will usually be adapted only to receive a fairly largediameter wire and in the past recourse has been had to an adaptor to accommodate smaller wires in plugs of relatively large diameters. It will be apparent that the instant invention obviates the need for such an adaptor in that the wire is crimped directly onto the terminal itself. Another distinct advantage of the invention is that, as shown in Figure 11, the axis of the wire as crimped in the connector is in substantial alignment with the axis of the plug itself and furthermore is in axial alignment with the crimped strands on the ends of the wire. In many prior art connectors, where the wire is crimped in its uninsulated end portion, the axis of the wire will be displaced from the axis of the end strands which are crimped to the connector and this is undesirable in that the strands are bent near their ends and thus weakened. The instant invention avoids thiscondition by deforming or crimping the connector from both sides towards its central axis to pinch the conducting strands and crimp them to the connector. A further advantage of the invention is that a range of wire sizes can be accommodated in a single size connector by controlling the extent to which the base of the connector is indented to form web 42 and further by controlling the extent to which the sidewalls and their edges are bent down toward the web. It will be obvious from Figure 7 that if the web 42 were somewhat shallower than that shown (i.e., if the flanges 43 or 44 were not so high above the surface of the web), a larger wire could be crimped in the same size terminal. Alternatively, the smaller wire can be adopted by making the flanges even larger and pressing or curling the sidewalls into closer engagement with the strands and toward'the web. These latter advantages of the invention inure to uses other than in conjunction with plug type terminals as shown in the drawing, for example, terminals having ring tongue end portions or spade end portions.

While we have disclosed a preferred embodiment of our invention and the method of practicing it, it will be obvious to those skilled in the art that it is amenable to alternative uses and to alternative arrangements of the parts.

We claim:

1. The method of crimping onto a conductor having a stripped end the ferrule-forming portion of a connector, said ferrule-forming portion having a base and a pair of sidewalls extending therefrom, and providing a pair of slots extending transversely across said base and partially on said sidewalls, said method comprising the steps of: supporting the base of said ferrule-forming portion between said slots on an anvil, positioning a conductor within said ferrule-forming portion with its stripped end extending between said slots and with unstripped portions extending beyond said slots, displacing said ferrule forming portion toward and over said anvil to form between said slots a web having reversely bent flanges extending from the longitudinal edges thereof which flanges merge with said sidewalls while simultaneously positioning end portions of said ferrule-forming portion on a second anvil, bending the longitudinal edge portions of said sidewalls contained between the planes of said slots inwardly towards each other and downwardly towards said web to form a crimped connection in the zone between the planes of said slots between said stripped end and said ferrule-forming portion, and bending end portions of said sidewalls towards each other to form an insulation supporting ferrule for said conductor.

2. An electrical connection formed from an initially trough-like connector having a base and upstanding sidewalls, said connector being crimped into engagement with a conductor to form an electrical connection with the conducting strands of said conductor and an insulation supporting ferrule around insulated portions of said conductor, said electrical connection comprising a web formed by inward displacement of said base and having flanges extending from the longitudinal edges thereof, said flanges being reversely curled and merging with said connector sidewalls, said sidewalls being curled towards each other and into engagement with said conducting strands, said insulation supporting ferrule comprising portions of the base of said connector in substantially undeformed condition and adjacent sidewalls, said adjacent sidewalls being bent towards each other and into surrounding relationship with insulated portions of said conductor.

3. A connector as set forth in claim 2 wherein said insulation supporting ferrule provides protrusions on its interior surface in compressing engagement with said insulated portions of said conductor.

4. The method of crimping the ferrule-forming portion of an electrical connector providing a base having sidewalls extending therefrom onto a conductor, said method comprising the steps of: positioning the stripped end of at least one insulated conductor within said ferruleforming portion with insulation adjacent the end of said conductor disposed within the end section of said ferrulefc-rming portion, indenting the base of said ferrule-forming portion upon itself in the vicinity of said stripped end to form a web having reversely bent flanges extending from the longitudinal edges thereof while substantially simultaneously bending said sidewalls in the vicinity of said stripped ends towards each other and towards said web to form a crimped connection between said stripped end and said connector in the vicinity of said stripped end, and bending said sidewalls of the end section of said ferrule-forming portion towards each other to form an insulation supporting ferrule for said connector.

5. An electrical connector comprising a contact plug portion having an electrical connection with a conductor and having an insulation support for said conductor, said electrical connection and said insulation support having been formed from an initially trough-like portion of said connector having a base and upstanding sidewalls, said electrical connection comprising a web formed by inward displacement of said base and having flanges extending from the longitudinal edges thereof, said flanges being reversely curled and merging with said sidewalls, said sidewalls being curled towards each other and into engagement with the metallic core of said conductor, said insulation support comprising the base of said troughlike portion in substantially undeformed condition and adjacent sidewalls, said adjacent sidewalls being bent towards each other and into surrounding and gripping relationship with insulated portions of said conductor.

References Cited in the file of this patent UNITED STATES PATENTS 2,034,090 Douglas Mar. 17, 1936 2,343,522 Bergman Mar. 7, 1944 2,557,126 Macy June 19, 1951 2,697,213 Patton Dec. 14, 1954 2,729,695 Pierce Jan. 3, 1956 2,783,447 Watts Feb. 26, 1957 2,789,277 Schumacher Apr. 16, 1957 2,818,632 Hammell Jan. 7, 1958 OTHER REFERENCES Electrical Manufacturing, August 1948, Reprint (AMP) (pp. 1, 2 of 6 pp.).

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